1. Field of the Invention
The field of the present invention is containers including thermal insulation for holding hot liquids.
2. Background
U.S. Pat. Nos. 6,536,657 and 6,729,534, both to Van Handel, disclose a shrink film secured to the interior of the container. The shrink film is adapted to shrink when a hot liquid is placed into the container, thereby forming an insulating void between the shrink film and the wall of the container. U.S. Patent Publication No. 2005-0029337 in the name of Van Handel describes further improvement on the container using shrink film to form the insulating void.
Other configurations for thermally insulated cups are also known. For example, the insulated cup disclosed in U.S. Pat. No. 3,737,093 to Amberg et al. uses a plastic cup placed within a paper cup to create an air space for thermal insulation. Another insulated cup is disclosed in U.S. Pat. No. 4,435,344 to Iioka. This cup is formed of a paper cup coated with a thermoplastic synthetic resin film which is subsequently heated to form a foam insulating layer. U.S. Pat. No. 5,952,068 to Neale et al. discloses a cup insulation layer formed from syntactic foam, a type of foam which incorporates insulating particles, which may contain an air space, held in place by a binder.
The disclosure of each of the above-mentioned documents are incorporated herein by reference.